The above map is an illustration
of what Celtic Britian may have looked like at around
440 CE.

Celtic Britain was not
peaceful within itself as it is recorded (by Gildas
100 years later) that Vortigern, who was believed to
be recognized as a leading Celtic warrior leader if not a king, invited a Saxon
led mercenary force led by Hengist to Britain to
fight in a war against the Picts. This gave the
Saxons a foothold to mound an invasion.